Does an increase in airflow (intake or exhaust runner) move peak torque up or down the RPM band?

Since plenum and runner volume have all kinds of RPM range applications we have to realize that the intake affects everything to do with HP, TQ as well as the range in RPM's that they produce them.
So it's not just the cam that determines.

The actual answer to your specific question the way you asked is both HP and TQ are increased with more flow.